The usual hybrid power modules (HPM) in power inverter for motor drives is well known. The power modules include associated power switches and other related functions. A common method of mounting these devices is by inserting a screw in each of the mounting holes provided at each corner thereof with the screw engaging threaded holes in a chassis. These power modules generate excessive heat and therefore include a thermally conductive baseplate to dissipate the excessive heat. The baseplate is typically a metallic plate in thermal communication with the power switches of the module.
It is also known for a hybrid power module to be mounted over an opening of a fluid manifold so that liquid coolant flowing through the manifold comes into direct contact with the coolant for cooling the power module. This arrangement has the advantage of a more efficient cooling than using ambient air. The environment of the power module and/or the ambient air surrounding the power module typically does not provide efficient cooling. The baseplate of the power module is sealed to the coolant manifold by an O-ring seal to prevent coolant from leaking from the manifold. Accordingly, a consistent force across each edge of the module is desired to ensure that the O-ring does not leak over its design life and environment.
Typically, the power module is mounted to the manifold by four bolts at the corners of the power module (through the aforementioned mounting  holes). The bolts pass through respective mounting holes in the baseplate and tightened within threaded holes in the manifold. The long space between mounting holes located at the corners allows the center portion of the edge of the baseplate to deflect. This deflection can cause a leak. The base plate has also been provided with a plurality of mounting holes intermediate the corner holes to prevent the deflection of the baseplate. While the additional mounting holes allow the power module to be securely mounted to the cooling manifold, this configuration increases the cost and labor to mount the power module. In addition, the intermediate mounting holes take up valuable space which could be used to mount devices or reduce the size of the power module.